The two dozen U.S. Postal Service workers, all members of the American Postal Workers Union, were clad in blue shirts and armed with signs reading, “Stop Staples,” as they broke out into chants, waving at passing motorists along Marketplace Boulevard today.

Heading to or coming from their shifts at the Postal Service’s distribution center across the street on Route 130, the union members stopped to protest outside the office supplies store, where customers may soon be able to rely on as a post office alternative.

Under the terms of the Postal Services’ “Retail Partner Expansion Program,” many Staples customers can now receive postal services — such as packing, shipping and stamp sales — at 80 stores as part of a pilot program, not yet available in the northeast.

Bill Lewis, president of the American Postal Workers Union Trenton Metro Area Local, said he fears the program will soon expand nationwide and turn the Postal Service into a private enterprise.

“With all the concern about privacy and identity theft, that’s just not the right way to handle the U.S. mail,” Lewis said. “Mail should be handled by highly trained, experienced postal employees, who swear an oath to protect your letters and packages and who are accountable to the American people. This program is compromising service to our customers.”

The protest in Hamilton was part of the American Postal Workers Union’s National Day of Action at more than 50 locations in 27 states.

“Staples makes business decisions based on the bottom line, not service to the people of the country,” American Postal Workers Union president Mark Dimondstein said in a news release. “As a nation, we need to decide what kind of Postal Service we want. Are we going to have a vibrant, modern, public mail system that serves all of the people, or are we going to let privatizers kill this great institution?”

Dimondstein referred to a Postal Service memorandum that notes the Postal Service could cut costs associated with the time of window clerks and credit card transaction fees. He said the memorandum makes it clear that the Staples program is designed to replace Postal Service employees with private sector workers.

In a statement, Postal Service spokesman Ray Daiutolo called the Staples program the “next logical step of providing expanded access to postal products and services.”

“The Retail Partner Expansion Program is an opportunity ‘to grow the business’ and has never been an earmark to pave a way to privatization. The Postal Service receives no tax dollars for operating expenses, and relies on the sale of postage, products and services to fund its operations,” Daiutolo said. “This retail partnership program could be an innovative step towards generating revenue to ensure the long-term viability of the Postal Service.”

In 2011, the Postal Service cited an ongoing decline in mail volume and a need to streamline operations when it closed branches in the Yardville neighborhood of Hamilton and the Chambersburg neighborhood of Trenton.